UPDATE: From restaurant meals to late fees -- which expense is your biggest waste of money?2-9-18 4:22 PM EST

By Maria LaMagna

Commenters on Reddit confess their biggest money wasters

Savvy consumers love to share their personal money-saving strategies, but what about their money-wasting confessions?

It's a personal question, but plenty of people wanted to weigh in on a popular Reddit thread (https://www.reddit.com/r/Frugal/comments/7vwwub/whats_the_biggest_waste_of_money/) this week. A Reddit user by the name "hibiki777" posted to a discussion about frugality Wednesday and simply asked, "What's the biggest waste of money? I'm thinking dining, but I've already cut that out." Another suggested "interest and late fees" are the biggest wastes of money, and one user said "buying stuff because it's on sale."

Generation X and millennials are neck-in-neck in regretting spending on nonessentials (43% each versus 31% for boomers). Indeed, half of millennials regret spending money on coffee and also eating out at restaurants, while 61% regret fast food (http://www.marketwatch.com/story/the-no-1-financial-regret-of-millennials-and-they-dont-have-many-2017-09-15) and 97% regret bank fees, according to a survey released last year by Durham, N.C.-based Common Cents Lab, a financial research lab at Duke University.

Dining out can add up

Preparing oatmeal at home, three times a week for a whole year, would cost about $24.96, according to a calculation from Credit.com. Buying that same amount of oatmeal would cost $310.44 from McDonald's (http://www.marketwatch.com/story/the-16-cent-breakfast-that-is-perfect-for-every-morning-2016-05-03) and $538.20 at Starbucks.

And more Americans are eating out than ever before (http://www.marketwatch.com/story/why-millennials-dont-know-how-to-cook-2016-08-10). For the first time ever, Americans in 2014 spent more money on food away from home than food prepared and consumed at home, according to the U.S. Department of Agriculture's Economic Research Service. Spending at "away from home" locations including restaurants, school cafeterias and sports venues made up 50.1% of the $1.46 trillion Americans spent on food for the year, with the remaining 49.9% going toward grocery-store purchases.

Small sacrifices lead to big savings. To combat the idea of forgoing lattes in the name of becoming a millionaire, Beth McMillan, a Ph.D. student in the computer science at the University of Oxford, found that, if instead of buying a latte, you invested 3 euros (http://www.marketwatch.com/story/making-your-own-latte-every-morning-could-save-you-337942-2017-03-10) ($3.19 in U.S. dollars) for every day you bought a latte into an account that paid 6% interest for 50 years, you'd end up with 318,135.57 euros, or $337,942.69.

Late fees are easily avoidable

Reddit user "williamwilliam2" said was his biggest waste was interest and late fees, and he's not alone. Many Americans lose money on interest, especially on credit cards, which can have annual percentage rates APRs of 20% or more.

A recent analysis by CreditCards.com found that citizens of San Antonio have the hardest time paying off their credit-card debt, compared to debtors in other large U.S. cities.

The average credit cardholder in San Antonio has $7,070 in credit-card debt, CreditCards.com found. If citizens making the median income in San Antonio put 15% toward their debt each month, it would still take 22 months to pay it off (http://www.marketwatch.com/story/residents-of-these-cities-have-the-hardest-time-paying-their-credit-card-debt-2018-02-07), amounting to $911 in interest.

Many credit cards and loans also charge fees for paying a balance late.

Credit card companies must cap the late fee at $27 for cardholders (https://www.consumerfinance.gov/ask-cfpb/why-did-my-credit-card-issuer-increase-my-late-payment-fee-en-56/) who are late for the first time, and at $38 for any late payments within the next six billing cycles, according to rules set by the Consumer Financial Protection Bureau.

For consumers who have trouble paying their bills, that can add up.

Buying stuff just because it's on sale

Another commenter said the biggest waste of money is "buying stuff because it is on 'sale' that you otherwise wouldn't have purchased or needed; and also buying stuff that doesn't make you happy." Many others on Reddit agreed about not falling for cheap products. In fact, many consumers end up returning shoddy merchandise (http://www.marketwatch.com/story/consumers-return-6426-billion-in-goods-each-year-2015-06-18). "My dad calls this 'going broke saving money,'" one named "howtocleanyourpots" said.

"This is something I wish I'd learned much sooner," another said. When he was in his 20s, he bought "a lot of crap I didn't really need when it was on sale," until he made a spreadsheet that showed the total amount it all cost. "My jaw dropped," he said. Instead, spending more on quality brands -- and maintaining the items you already own -- can pay off, Monk_Philosophy said. "The poor man pays twice," another user agreed.

-Maria LaMagna; 415-439-6400; AskNewswires@dowjones.com

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